From ORAC's second link:
The Japan Self-Defense Force is barred from deploying military aircraft to Shimochijima airport, which has the longest runway in the Ryukyu Islands. Therefore, defense officials are thinking of using the F-35B at airports with shorter runways.
Pity that nobody makes a much less expensive fighter that can fly on and off a 1500-2000 meter runway all day long without breaking a sweat. Wait, what?
Otherwise, Izumo's size will limit its ability to support a large and complex (F-4-sized) aircraft, irrespective of how it takes off and lands.